Perpendicular magnetic recording systems have been developed for use in computer hard disc drives. An approach to perpendicular magnetic recording requires the use of recording media with a magnetically soft underlayer which provides a flux path from the trailing pole to the leading pole of the writer. The soft underlayer enables substantially stronger fields than can be generated with a ring head in conventional longitudinal recording systems. The soft underlayer also provides sharper field gradients which enable writing on high coercivity media. In addition, the soft underlayer also affects the recording head during a read operation. During the read back process, the soft magnetic underlayer produces the image of magnetic charges in the magnetic hard layer. It has been determined that there is asymmetry between the recording head and its image with respect to the recording layer. Accordingly, it has further been determined that due to this asymmetry, resolution of a perpendicular magnetic recording system with a soft underlayer is usually never better than resolution of an equivalent system without a soft underlayer.
The trend in the data storage industry has been to develop magnetic recording systems having high density recording capabilities. Perpendicular recording designs have the potential to support much higher recording densities than conventional longitudinal designs for various reasons. However, the described fundamental resolution degradation due to the use of a soft magnetic underlayer is not a desirable feature because it limits high density recording in a perpendicular magnetic recording system that utilizes a soft underlayer.
There is identified, therefore, a need for an improved perpendicular magnetic recording head which overcomes disadvantages, limitations, or shortcomings of known perpendicular magnetic recording heads.